The present invention relates, in general, to manufacturing processes, and more particularly, to methods of calibrating manufacturing equipment.
In the past, various techniques have been utilized to maintain the accuracy of equipment used to manufacture semiconductor devices, such as equipment used to measure the thickness of dielectric layers formed on semiconductor wafers. One particular calibration technique is to utilize a semiconductor wafer having a known dielectric thickness formed thereon as a calibration standard. Periodically, the dielectric layer on the calibration standard is measured by the manufacturing equipment that is in use in the manufacturing area. Any variance in the measurements on the calibration standard from the known dielectric thickness on the calibration standard is assumed to be error or drift in the manufacturing equipment. The manufacturing equipment is then corrected either by repair or adjustments. Often, the manufacturing equipment has not drifted and is making accurate measurements. Consequently, the repair or adjustments result in inaccurate measurements of dielectrics in the manufacturing area thereby resulting in improperly manufactured semiconductor devices and increased manufacturing costs.
Accordingly, it is desirable to have a manufacturing method that provides accurate calibration of manufacturing equipment, that results in accurate measurements of semiconductor devices in the manufacturing area, and that reduces manufacturing costs.